US4428918A - Process and plant for the preparation of concentrated aqueous solutions of alkali metal hypochlorite - Google Patents

Process and plant for the preparation of concentrated aqueous solutions of alkali metal hypochlorite Download PDF

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Publication number
US4428918A
US4428918A US06/326,273 US32627381A US4428918A US 4428918 A US4428918 A US 4428918A US 32627381 A US32627381 A US 32627381A US 4428918 A US4428918 A US 4428918A
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alkali metal
aqueous solution
reaction chamber
suspension
crystals
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English (en)
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Jean Verlaeten
Jacques Brahm
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Solvay SA
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Solvay SA
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B11/00—Oxides or oxyacids of halogens; Salts thereof
    • C01B11/04—Hypochlorous acid
    • C01B11/06—Hypochlorites
    • C01B11/062—Hypochlorites of alkali metals

Definitions

  • the present invention has for its aim a process and plant for the preparation of concentrated aqueous solutions of alkali metal hypochlorite, for example sodium hypochlorite, having a strength greater than 63 chlorometric degrees.
  • alkali metal hypochlorite for example sodium hypochlorite
  • Javel extracts are dilute aqueous solutions of sodium hypochlorite having a strength between 30 and 70 chlorometric degrees, normally between 35 and 50 chlorometric degrees.
  • the strength of an aqueous solution of alkali metal hypochlorite in chlorometric degrees is defined as the amount of liters of gaseous chlorine at 0° C. and 1 bar having the same oxidizing power as one liter of the solution at 20° C.
  • Javel extracts can be prepared by reacting chlorine, possibly diluted with air, with aqueous solutions of sodium hydroxide.
  • the resulting extracts of Javel are therefore aqueous solutions of sodium hypochlorite, containing dissolved sodium chloride, and their stability over a period of time is uncertain.
  • This known process has the disadvantage that it is not adapted to a continuous production of solutions of sodium hypochlorite with a constant strength.
  • the invention aims to remove these disadvantages of the known processes, by supplying a process for the production of aqueous solutions of alkali metal hypochlorite of high strength which allows easy separation of the crystals of sodium chloride and which can be installed in an inexpensive plant, easy and reliable to operate and allowing a continuous production of solutions of sodium hypochlorite.
  • the invention concerns, in consequence, a process for the preparation of concentrated aqueous solutions of alkali metal hypochlorite, wherein a suspension of crystals of alkali metal chloride in an aqueous solution of alkali metal hypochlorite is used in a reaction chamber, an aqueous solution of alkali metal hydroxide and a gas containing chlorine are introduced in the aqueous suspension and an aqueous solution of alkali metal hypochlorite and crystals of alkali metal chloride are removed out of the reaction chamber; according to the invention the gas is introduced into the lower part of the reaction chamber so as to subject the suspension to a rising displacement by gasosiphon, the suspension is drawn-off from the upper part of the reaction chamber and separated into at least two fractions, one of the fractions is recycled to the base of the reaction chamber and the aqueous solution of alkali metal hypochlorite and the crystals of alkali metal chloride are recovered separately from the other fraction.
  • the concentrated aqueous solutions of alkali metal hypochlorite are solutions of alkali metal hypochlorite, for example sodium or potassium hypochlorite whose available chlorine content should be high enough for their production by reaction of a gas containing chlorine with an aqueous solution of alkali metal hydroxide to be accompanied by crystallisation of alkali metal chloride.
  • a strength of 63 chlorometric degrees is the minimum value to be aimed at.
  • dilution gas is made from those which do not react with chlorine or with alkali metal hydroxide in the operating conditions of the process. It can, for example, be air.
  • waste gas from the liquefaction of chlorine produced by the electrolysis of an alkali metal chloride brine is used.
  • a waste gas usually contains, as its main constituents, chlorine, carbon dioxide and air; the partial pressure of the chlorine in this gas is usually between 5 and 10% of the total gas pressure.
  • the aqueous solution of alkali metal hydroxide which is reacted with chlorine in the reaction chamber may with advantage be a dilute aqueous solution containing for example 300 to 500 g of sodium or potassium hydroxide per kg, obtained by electrolysis of a substantially saturated brine of sodium or potassium chloride in a mercury cathode cell or a cell with a non porous cation-exchange membrane.
  • this dilute aqueous solution of alkali metal hydroxide can be concentrated by evaporation, before being reacted with chlorine in the reaction chamber.
  • the upward velocity of the gas in the reaction chamber should be sufficient to ensure upward displacement of the suspension of crystals in the reaction chamber up to the point where it is drawn-off from it. It is controlled mainly as a function of its chlorine content, of the concentration of the solution of sodium hydroxide and its rate of flow into the reaction chamber, as well as the construction characteristics of said chamber.
  • the preferred velocities are those between 0.25 and 1.5 m/s, the best results have been obtained with velocities between 0.50 and 1 m/s.
  • the recycling, inside the reaction chamber, of a fraction of the suspension drawn-off from it ensures the production of crystals of alkali metal chloride which can then be separated easily and economically, from the concentrated solution of alkali metal hypochlorite.
  • the ratio between the weight of the fraction of recycled suspension and the total weight of suspension drawn-off from the reaction chamber is chosen as a function of the particule size which is desired for the crystals of alkali metal chloride in the suspension drawn-off from the reaction chamber, when the process has reached steady operating conditions.
  • This ratio is in general greater than a minimum critical value, below which the average diameter of the crystals of alkali metal chloride in the suspension drawn-off from the reaction chamber becomes insufficient to allow their separation easily and economically.
  • the lower and higher critical values specified depend on a large number of factors, most important of which are the height of the reaction chamber, the rising velocity of the suspension, the chlorine content of the gas, the strength required for the concentrated solution of alkali metal hypochlorite and the choice of equipment used to separate the crystals of alkali metal chloride from the said solution. They can be determined, in each particular case by a routine laboratory test.
  • Separation of the crystals of alkali metal chloride from the fraction of aqueous suspension which is not recycled, can be carried out by any known suitable technique, for example by filtration, by settling and decanting or by centrifuging.
  • a pre-treatment with chlorine to form dissolved alkali metal hypochlorite.
  • This pre-treatment is preferably controlled in such a way as to avoid crystallising the alkali metal chloride; it can be carried out with a stream of waste gas leaving the reaction chamber and still containing a little chlorine.
  • the heat produced by reaction of the chlorine with the solution of alkali metal hydroxide in the reaction chamber is removed from the outside.
  • This removal of heat can be carried out by any known means, for example by means of a jacket fitted around the reaction chamber, and through which is flowing a cooling fluid, or by means of a tubular cooler fitted inside the reaction chamber.
  • the recycled fraction in order to remove at least part of the heat of reaction, is cooled, before being reintroduced into the reaction chamber.
  • the invention also concerns a plant for the operation of the process according to invention, comprising an enclosure, a vertical column open at top and bottom ends and located in the enclosure, a pipe for the admission of a gas containing chlorine in the enclosure, a pipe for the admission of an aqueous solution of alkali metal hydroxide in the enclosure and a means for removal out of the enclosure, of crystals of alkali metal chloride and an aqueous solution of alkali metal hypochlorite, the said plant being designed in such a way that the gas inlet pipe opens into the column, near to its bottom end, and the means for the removal of the crystals and the solution of alkali metal hypochlorite comprises a pipe which opens into the enclosure and discharges into a device for separating the crystals of alkali metal chloride and the solution of alkali metal hypochlorite.
  • the zone of the enclosure where the pipe for the admission of the aqueous solution of alkali metal hydroxyde emerges is preferably chosen so that the aqueous suspension leaving the top of the column is substantially free from alkali metal hydroxide.
  • the pipe for the admission of the aqueous solution of alkali metal hydroxide may lead into the enclosure, outside the column and below the zone where the pipe for the removal of the suspension emerges.
  • the plant comprises a cooler connected to the enclosure, via a pipe for removal of a fraction of the suspension from the enclosure and a pipe for the return of the said fraction into the enclosure.
  • the concentrated aqueous solutions of alkali metal hypochlorite obtained by means of the process and the plant according to the invention generally show good stability with time. They are normally intended to be diluted with water for the production of commercial Javel extracts having for example a strength between 30 and 50 chlorometric degrees.
  • FIGURE shows diagrammatically, by way of example, one particular form of embodiment of the plant according to the invention.
  • the plant shown in the FIGURE comprises a vertical cylindrical enclosure (1) in which is fixed an axial tubular column (2), open at both top and bottom ends.
  • Column (2) constitutes the actual reaction chamber in the installation; it communicates, at its lower part, with a pipe (3) for admission of an aqueous solution of alkali metal hydroxide and with a vertical pipe (4) for admission of a gas containing chlorine.
  • a distribution grid (5) ensures even distribution of the gas in vertical threads across the horizontal section of the column (2).
  • a pipe (6) leads into the annular zone (7) demarcated between the lateral wall of the enclosure (1) and the column (2); it serves to drawn-off a fraction of the concentrated aqueous solution of alkali metal hypochlorite formed in the raction chamber and containing crystals of alkali metal cloride in suspension, and to transfer it into a filtration device (8) to separate the crystals of alkali metal chloride.
  • the reaction chamber (2) is filled with an aqueous solution of alkali metal hypochlorite, saturated with alkali metal chloride, in which the crystals of alkali metal chloride are dispersed.
  • This suspension is carried to the top of the reaction chamber (2), by gasosiphon under the action of the current of gas admitted by the pipe (4).
  • an aqueous solution of alkali metal hydroxide is introduced in the suspension by pipe (3).
  • the chlorine gas reacts with alkali metal hydroxide to produce alkali metal hypochlorite and alkali metal chloride.
  • a fraction of the suspension overflows from the annular chamber (7) by the pipe (6) and is led to the filtration apparatus (8), while the remaining fraction (10) is recycled to the base of the reaction chamber (2).
  • a cake (11) of crystals of alkali metal chloride is separated and a concentrated aqueous solution of alkali metal hypochlorite (12) is recovered.
  • This solution having a strength greater than 63 chlorometric degrees can be diluted with water to produce a commercial Javel extract, having for example a strength of about 50 chlorometric degrees.
  • the plant comprises in addition an external cooler (13) connected in parallel with the annular chamber (7) via a pipe (14) and a pump (15) for extraction of a fraction of the aqueous suspension present there and a pipe (16) for recycling.
  • the waste gas collected in (9) is washed with the solution of alkali metal hydroxide, before being introduced into the reaction chamber (2), in order to absorb the chlorine which it might possibly contain.
  • an aqueous solution containing 33.5% by weight of sodium hydroxide was treated with a gas consisting of a mixture of air and chlorine and containing 5% by weight of chlorine.
  • the installation was supplied, via pipes (4) and (6) respectively, with hourly amounts of 2786 m 3 normal of gas and 1603 kg of the sodium hydroxide solution, so as to set up a rising velocity of about 0.70 to 0.80 m/s in the chamber (2).
  • the temperature inside the latter was kept at about 30° C.
  • the aqueous suspension circulating from top to bottom in the annular chamber (7) was a suspension of crystals of sodium chloride in an aqueous solution of sodium hypochlorite having a strength close to 100 chlorometric degrees; it contained 11% by weight of crystals of sodium chloride.
  • a filter cake (11) is separated, containing, by weight, 80.1% of sodium chloride and 19.9% of sodium hypochlorite and 1775 kg per hour of an aqueous solution of sodium hypochlorite is recovered, containing, per kg, 257 g of sodium hypochlorite and 94 g of dissolved sodium chloride.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Agricultural Chemicals And Associated Chemicals (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
  • Oxygen, Ozone, And Oxides In General (AREA)
US06/326,273 1980-12-22 1981-12-01 Process and plant for the preparation of concentrated aqueous solutions of alkali metal hypochlorite Expired - Lifetime US4428918A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8027409A FR2496628A1 (fr) 1980-12-22 1980-12-22 Procede et installation pour la preparation de solutions aqueuses concentrees d'hypochlorite de metal alcalin
FR8027409 1980-12-22

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US (1) US4428918A (Direct)
EP (1) EP0054996B1 (Direct)
AT (1) ATE10357T1 (Direct)
BR (1) BR8108231A (Direct)
DE (1) DE3167344D1 (Direct)
ES (1) ES508170A0 (Direct)
FR (1) FR2496628A1 (Direct)
PT (1) PT74175B (Direct)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4780303A (en) * 1982-08-24 1988-10-25 Produits Chimiques Ugine Kuhlmann Continuous process for the preparation of high strength sodium hypochlorite solutions
US4857292A (en) * 1986-12-15 1989-08-15 Solvay & Cie (Societe Anonyme) Process for the production of calcium hypochlorite and product obtained by this process
WO1991011387A1 (en) * 1990-02-01 1991-08-08 Olin Corporation Process for the production of highly pure concentrated solutions of potassium hypochlorite
WO1992017399A1 (en) * 1991-03-26 1992-10-15 Olin Corporation Process for producing slurries of sodium hypochlorite
US5194238A (en) * 1991-03-26 1993-03-16 Olin Corporation Process for the production of highly pure concentrated slurries of sodium hypochlorite
US20050169832A1 (en) * 2004-02-02 2005-08-04 Powell Technologies Llc Concurrent packed tower manufacture of hypochlorite
WO2005121021A1 (en) * 2004-06-07 2005-12-22 Powell Technologies Llc Concurrent low-pressure manufacture of hypochlorite
US20060008409A1 (en) * 2004-07-12 2006-01-12 Powell Technologies Llc Manufacture of high-strength, low-salt sodium hypochlorite bleach
US20070110662A1 (en) * 2004-07-12 2007-05-17 Powell Duane J Manufacture of high-strength, low-salt sodium hypochlorite bleach
US20070114489A1 (en) * 2004-07-12 2007-05-24 Powell Technologies Llc Manufacture of high-strength, low-salt aqueous sodium hypochlorite bleach and substantially dry crystalline salt
WO2008068191A1 (en) * 2006-12-04 2008-06-12 Akzo Nobel N.V. Process to prepare concentrated alkali metal hypo-chlorite
CN101027249B (zh) * 2004-07-12 2011-08-17 鲍威尔技术有限责任公司 高浓度、低盐次氯酸盐漂白剂的制造
CN101668699B (zh) * 2006-12-29 2013-05-08 鲍威尔技术有限责任公司 高浓度的低盐的次氯酸钠漂白剂的制造
US20140117278A1 (en) * 2012-10-31 2014-05-01 Olin Corporation Sodium hypochlorite composition and method of storing and transporting sodium hypochlorite

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2680165B1 (fr) * 1991-08-06 1993-10-15 Atochem Procede de preparation de solutions concentrees d'hypochlorite de metal alcalin.

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1005936B (de) 1955-11-30 1957-04-11 Hoechst Ag Verfahren zur Herstellung von Loesungen von Hypochloriten
GB934378A (en) 1959-10-29 1963-08-21 Gen Mills Inc Higher amino hydroxy nitriles and their production
US3287233A (en) 1962-12-20 1966-11-22 Electro Chimie Metal Process for manufacture of javel extracts
US3582262A (en) 1965-02-15 1971-06-01 Universal Oil Prod Co Multiple stage method for removing chlorine and entrained aluminum chloride particles from a waste gas stream
US3870782A (en) 1971-06-11 1975-03-11 Mississippi Chem Corp Ammonium nitrate neutralizer
US3917475A (en) 1974-04-12 1975-11-04 Allied Chem Liquid fertilizer composition and process
US4094643A (en) 1976-09-16 1978-06-13 Mississippi Chemical Corporation Ammonium nitrate neutralizer
US4234560A (en) 1976-10-09 1980-11-18 Basf Aktiengesellschaft Process for treating a liquid with a gas and for preventing the phase separation of unreacted gas and liquid, in a circulatory reactor
US4238462A (en) 1978-01-31 1980-12-09 Air Resources, Inc. Autocirculation process and apparatus

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB984378A (en) * 1962-10-24 1965-02-24 Murgatroyds Salt & Chem Improvements in or relating to sodium hypochlorite production
JPS54118398A (en) * 1978-03-07 1979-09-13 Asahi Glass Co Ltd Preparation of high concentration aqueous sodium hypochlorite solution

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1005936B (de) 1955-11-30 1957-04-11 Hoechst Ag Verfahren zur Herstellung von Loesungen von Hypochloriten
GB934378A (en) 1959-10-29 1963-08-21 Gen Mills Inc Higher amino hydroxy nitriles and their production
US3287233A (en) 1962-12-20 1966-11-22 Electro Chimie Metal Process for manufacture of javel extracts
US3582262A (en) 1965-02-15 1971-06-01 Universal Oil Prod Co Multiple stage method for removing chlorine and entrained aluminum chloride particles from a waste gas stream
US3870782A (en) 1971-06-11 1975-03-11 Mississippi Chem Corp Ammonium nitrate neutralizer
US3917475A (en) 1974-04-12 1975-11-04 Allied Chem Liquid fertilizer composition and process
US4094643A (en) 1976-09-16 1978-06-13 Mississippi Chemical Corporation Ammonium nitrate neutralizer
US4139601A (en) 1976-09-16 1979-02-13 Mississippi Chemical Corporation Ammonium nitrate neutralization
US4234560A (en) 1976-10-09 1980-11-18 Basf Aktiengesellschaft Process for treating a liquid with a gas and for preventing the phase separation of unreacted gas and liquid, in a circulatory reactor
US4238462A (en) 1978-01-31 1980-12-09 Air Resources, Inc. Autocirculation process and apparatus

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Chemical Abstracts, vol. 78, No. 6, Feb. 1973, 32184q.

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4780303A (en) * 1982-08-24 1988-10-25 Produits Chimiques Ugine Kuhlmann Continuous process for the preparation of high strength sodium hypochlorite solutions
US4857292A (en) * 1986-12-15 1989-08-15 Solvay & Cie (Societe Anonyme) Process for the production of calcium hypochlorite and product obtained by this process
WO1991011387A1 (en) * 1990-02-01 1991-08-08 Olin Corporation Process for the production of highly pure concentrated solutions of potassium hypochlorite
US5055285A (en) * 1990-02-01 1991-10-08 Olin Corporation Process for the production of highly pure concentrated solutions of potassium hypochlorite
WO1992017399A1 (en) * 1991-03-26 1992-10-15 Olin Corporation Process for producing slurries of sodium hypochlorite
US5194238A (en) * 1991-03-26 1993-03-16 Olin Corporation Process for the production of highly pure concentrated slurries of sodium hypochlorite
US20050169832A1 (en) * 2004-02-02 2005-08-04 Powell Technologies Llc Concurrent packed tower manufacture of hypochlorite
WO2005121021A1 (en) * 2004-06-07 2005-12-22 Powell Technologies Llc Concurrent low-pressure manufacture of hypochlorite
US7175824B2 (en) 2004-07-12 2007-02-13 Powell Technologies Llc A Michigan Limited Liability Company Manufacture of high-strength, low-salt sodium hypochlorite bleach
US8491864B2 (en) * 2004-07-12 2013-07-23 Powell Technologies Llc Manufacture of high-strength, low-salt sodium hypochlorite bleach
US20060008409A1 (en) * 2004-07-12 2006-01-12 Powell Technologies Llc Manufacture of high-strength, low-salt sodium hypochlorite bleach
US20070110662A1 (en) * 2004-07-12 2007-05-17 Powell Duane J Manufacture of high-strength, low-salt sodium hypochlorite bleach
US20070114489A1 (en) * 2004-07-12 2007-05-24 Powell Technologies Llc Manufacture of high-strength, low-salt aqueous sodium hypochlorite bleach and substantially dry crystalline salt
US8623318B2 (en) 2004-07-12 2014-01-07 Powell Technologies Llc Manufacture of high-strength, low-salt aqueous sodium hypochlorite bleach and substantially dry crystalline salt
EA010679B1 (ru) * 2004-07-12 2008-10-30 Пауэлл Текнолоджиз Ллс (Э Мичиган Лимитед Лайабилити Компани) Способ производства отбеливающего средства
WO2006017234A3 (en) * 2004-07-12 2006-07-06 Powell Technologies Llc A Mich Manufacture of high-strength, low-salt hypochlorite bleach
CN101027249B (zh) * 2004-07-12 2011-08-17 鲍威尔技术有限责任公司 高浓度、低盐次氯酸盐漂白剂的制造
US20100084605A1 (en) * 2006-12-04 2010-04-08 Akzo Nobel N.V. Process to prepare concentrated alkali metal hypo-chlorite
WO2008068191A1 (en) * 2006-12-04 2008-06-12 Akzo Nobel N.V. Process to prepare concentrated alkali metal hypo-chlorite
CN101668699B (zh) * 2006-12-29 2013-05-08 鲍威尔技术有限责任公司 高浓度的低盐的次氯酸钠漂白剂的制造
US20140117278A1 (en) * 2012-10-31 2014-05-01 Olin Corporation Sodium hypochlorite composition and method of storing and transporting sodium hypochlorite
US9434616B2 (en) * 2012-10-31 2016-09-06 Olin Corporation Sodium hypochlorite composition and method of storing and transporting sodium hypochlorite

Also Published As

Publication number Publication date
FR2496628A1 (fr) 1982-06-25
PT74175A (fr) 1982-01-01
DE3167344D1 (en) 1985-01-03
ES8304031A1 (es) 1983-02-16
ATE10357T1 (de) 1984-12-15
ES508170A0 (es) 1983-02-16
PT74175B (fr) 1983-05-17
BR8108231A (pt) 1982-10-05
FR2496628B1 (Direct) 1985-02-01
EP0054996A1 (fr) 1982-06-30
EP0054996B1 (fr) 1984-11-21

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